This invention concerns an electrically conductive flexible sheath or jacket for wire bundles, pipes or the like. The jacket has longitudinal fastening means along its length for installation and removal.
For many years, flexible jackets have been marketed for wire bundles or the like. A representative jacket has an elongated plastic sheet with means along each longitudinal edge for securing the two edges together to form a tubular jacket. This edge-fastening means make take a variety of forms, as disclosed in U.S. Pat. Nos. 3,089,915; 3,234,614; 3,350,752; 3,808,665; 3,858,282 and 4,513,484 for example. Such a plastic jacket can be wrapped around a bundle of wire and the two moieties of the fastening means secured together to make a more or less cylindrical sheath surrounding the wire. Such jackets are used to keep the bundle of wires together.
It is sometimes desirable to contain a bundle of wires in an electrically conductive jacket so that the jacket can be grounded to prevent stray electrical fields from entering or leaving the wire bundle. Such a grounded jacket may be formed of braided wire which is slipped longitudinally over the bundle of wire. Clearly, this is inconvenient and may be impractical for very long wire bundles.
Such electrical shielding can also be provided by laminating flexible metal foil on one of a flexible removable plastic jacket, as described above. A grounding strap of braided wire may extend along the length of the jacket to improve electrical conductivity for grounding. When such a laminated jacket is wrapped around a wire bundle the contents can be electrically shielded.
In another embodiment, a knitted mesh of wire is stitched along an edge of a flexible plastic jacket. The same stitching may be used for securing a braided wire grounding strap in good electrical contact with the wire mesh. When such a jacket is secured tightly around a wire bundle, the edges of the mesh and grounding strap overlap to provide a substantially continuous electrically conductive layer around the bundle.
In such an embodiment, if the jacket envelops a wire bundle having a diameter appreciably smaller than the diameter of the jacket, the jacket will be loose on the bundle and can collapse. Continuity of the conductive jacket may be interrupted, thereby opening the bundle to electromagnetic interference.
There may also be instances where it is desirable to provide an electrically conductive jacket alone without the additional layer of electrical insulation.
It may also be desirable to provide the electrically conductive jacket of an insulating jacket. This might be used for example to sheath a conductive pipe carrying electrical wires. The external conductive jacket may provide extra grounding or a signal may be imposed thereon to mask any stray signals that might be broadcast from a conductive pipe. Such an embodiment may be useful for assuring secure communications.
Additional electrical shielding can also be important for avoiding effects of electromagnetic pulse which may disable sensitive electronic components. Similarly, shielding can alleviate problems from lightning strikes.
It is a common feature of these areas that it is desirable to have a flexible electrically conductive jacket that can be reliably placed around the pipe, bundle of wires of the like, without feeding it on from one end. It is desirable that the overlap of the edges of such a jacket be secured so that there is an electrically continuous jacket around a wire bundle. It is often desirable that this be accompanied by an electrically insulating layer similarly applied. Such a jacket should be lightweight, economical and reliable. It should be easily installed and removed without special facilities or equipment.